This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background: To determine whether epididymal sperm could be retrieved and successfully cryopreserved testes were collected at necropsy from a total of 20 rhesus macaques. Methods: The males ranged in age from 3 to 19 years with an average of 8.5 years. No semen was obtained from three animals, which were younger than 4 years. The remaining 17 samples contained semen with an average sperm cell concentration of 144.0 mio/mL, an average motility of 72.8 % and a mean grade of 2.6. Results/Discussion: After 24 h of culture the overall motility decreased significantly in all samples regardless of treatment to 8.8 % in fresh non-activated and 3.8 % in activated semen at 24 hr. Freezing had a significant effect on semen reducing the mean grade to 1.6 and the immediate post-thaw motility to 42.4 % in non-activated samples. Activation further reduced semen motility after 4 hr in fresh semen (72.8 vs 50.4%), but increased it in semen that had been frozen (14.0 vs 23.2%). The age of the male did not influence semen concentration, grade or initial motility, but proved to be a significant factor in determining motility of frozen-thawed activated semen with lower motility found in samples from older males. Overall the study demonstrates that motile semen can be obtained from post-mortem males, although subsequent studies will have to determine whether the quality is sufficient to facilitate its use in assisted reproduction.